much importance to the city that the supply should be such as not only to answer the present purposes, but be adequate to the future increased demands, and that the quality of the water should be unquestionable, that it became necessary to extend the examinations over every watered district in the vicinity, in order to judge of the comparative merits of different sources. The Engineers who were employed, traversed the country, gauged the streams, reported their supply, the quality of the water, and plans which might be adopted for conveying it to the city. It was a field for the exercise of the talent and research of the Engineer : in resorting to a distant stream for a supply, any plan which he might propose for conveying the water, would encounter obstacles requiring skill and ingenuity to 18 70 overcome. He would find it necessary to build up the val- leys, pierce through the hills, and span the waters of the arms of the sea which embrace the city and make it an island. Structures would be required, which, in their de- sign, would find no parallel among the public works of this country, and in forming plans for them he might study with advantage, the works constructed for similar purposes by the Ancient Romans. The examinations embraced all the sources from which a supply of water might be obtained in the neighboring coun- ties of Westchester and Putnam ; giving a comparison of the different streams in regard to their elevation, their capa- city, and the quality of the water. It was decided that the Croton River would supply a sufficient quantity of water at all seasons of the year ; at an elevation precluding the use of steam or any other extraneous power, and that the quality of the water was unexceptionable. t)ther streams were found which would furnish water equally pure, but too limited in quantity at certain seasons of the year, and not at a sufficient elevation. In addition to the information furnished by the Engineers employed, the Water Commissioners received communica- tions from other sources suggesting plans for supplying the city with water. It was suggested that water might be obtained from the Passaic Falls, at a distance of about eighteen miles from the city, in New-Jersey. The objections to this project were, that it would be going into another state, that an Aqueduct bridge over the Hudson River would obstruct its navigation, and iron pipes laid across the bed of the 71 river would be exposed to injury from the anchors of the shipping. Another plan was proposed which contemplated a permanent dam across the Hudson River extending from the city to the Jersey shore. This dam was proposed to be built about 2 feet above the level of high tide, thereby keeping all the salt water below ; and above the dam would be the fresh water for supplying the city, which must be pumped up into a reservoir by means of water-wheels, which would be operated by the overfall of water when the tide was low, but when the tide was up within 2 feet of the top of the dam there would not be sufficient fall to propel the wheels. Locks were to be inserted in the dam, of a suffi- cient number to accommodate the vessels on the river. The river, at the place where it was proposed to locate the dam, is over a mile in width, and in the channel the depth below the surface to proper foundation for such a structure, would probably be 50 feet. The difference of tides is about 5 feet, which added to the height of dam above high tides, would give 7 feet of the top of the dam exposed to the pressure of the water on the up stream side when the tide is low. It was suggested that the hydraulic power here obtained, could be used for manufacturing purposes, except that por- tion of it which would be required for elevating the water to the reservoir. This plan of supplying the city with water was objected to, because it could not be accomplished ex- cept by an Act of the Legislature of New-Jersey as well as that of New- York, and it was also questionable whether such obstructions could be placed in navigable rivers without in- terfering with the powers of Congress to regulate the com- merce of the nation. It was feared that in locking vessels 72 through, the salt water would become mingled with the fresh above the dam where a supply would be taken for the city, to such a degree, that it would render it unfit for domestic use. The quantity of land that would be overflowed by the water set back by the dam, presented